The present invention relates to an improved fluid energy absorber device, such as a fluid spring or shock absorber, or combination of both, having a plastic casing and a separate screw-in plastic seal for the piston thereof.
A fluid energy absorber device having a plastic casing is shown in U.S. Pat. No. 3,618,928, and one having an integral molded seal is disclosed in U.S. Pat. No. 4,265,344.
The mold for molding a plastic casing for a fluid energy absorber device with an integral seal, such as shown in U.S. Pat. No. 4,265,344, is relatively expensive. Before a plastic energy absorber device of this type can be placed in use, it must be extensively tested. If changes are required, as a result of information obtained from the testing, the modification of the mold can involve considerable additional expense. Furthermore, the cost of the mold for energy absorber devices with plastic casings and integral molded seals is prohibitively high for short production runs.
In addition, some environments in which energy absorber devices are used are abrasive in nature, which will result in a short seal life, while the cylinder will still have a long life. Replaceable seals are desirable in these applications. It is with solving the foregoing problems that the present invention is concerned.